Materials for lithographic plates coatings, lithographic plates and coatings containing same, methods of preparation and use

Abstract

This invention relates to iodonium salts, acetal copolymers and polymer binders comprising functional groups capable of undergoing cationic or radical polymerization, their method of preparation and their use in the preparation of coating solutions and coatings. This invention also relates to coatings containing the iodonium salts, acetal copolymers and/or polymer binders and to negative working lithographic printing plates comprising these coatings.

1 . An acetal copolymer having attached thereto at least one functional group capable of undergoing cationic or radical polymerization, the acetal copolymer being: 
       
         
           
           
               
               
           
         
         wherein:
 G1 represents a processing segment providing solubility in organic solvents to the acetal copolymer; 
 G2 represents a thermal reactive segment; 
 G3 represents a radiation-absorbing segment exhibiting one or more strong absorption bands between 700 and 1100 nm; 
 a, b, c, d and e are molar ratios and may can vary from 0.01 to 0.99; 
 
       
       
         
           
           
               
               
           
         
         any of G1 and G2 may independently be replaced by 
       
       
         
           
           
               
               
           
         
       
       and
 said functional group is attached to G2 or G3. 
 
     
     
         2 . The acetal copolymer of  claim 1 , wherein G1 is linear alkyl, branched alkyl, linear aryl or branched aryl, wherein said linear alkyl, branched alkyl, linear aryl or branched aryl comprises a cyano, hydroxy, dialkylamino, trialkylammonium salt, ethylene oxide, propylene oxide methylbenzylsufonyl-carbamate, carboxylic acid or phosphoric acid functional group. 
     
     
         3 . The acetal copolymer of  claim 1 , wherein G2 is linear alkyl, branched alkyl, linear aryl or branched aryl, wherein said linear alkyl, branched alkyl, linear aryl or branched aryl has attached thereto, optionally via a linker group, said functional group. 
     
     
         4 . The acetal copolymer of  claim 3 , wherein said functional group is acrylate, methacrylate, vinyl ether, alkoxy-methyl acrylamide or alkoxy methacrylamide. 
     
     
         5 . The acetal copolymer of  claim 1 , wherein G3 is 
       
         
           
           
               
               
           
         
       
       wherein NIR is a near-infrared absorbing chromophore exhibiting one or more strong absorption peaks between 700 and 1100 nm. 
     
     
         6 . The acetal copolymer of  claim 5 , wherein said near-infrared absorbing chromophore is: 
       
         
           
           
               
               
           
         
         wherein:
 D1 and D2 are independently —O—, —S—, —Se—, —CH═CH—, and —C(CH3)2; 
 Z1 and Z2 each independently represent one or more fused substituted or unsubstituted aromatic ring; 
 h may vary from 2 to 8; 
 n represents 0 or 1; 
 M represents hydrogen or Na, K, or tetraalkylammonium salts cationic counter ion; 
 A1 represents bromide, chloride, iodide, tosylate, triflate, trifluoromethane carbonate, dodecyl benzosylfonate and tetrafluoroborate, tetraphenylborate or triphenyl-n-butylborate anionic counter ion; 
 R3 and R7 each independently represent hydrogen or alkyl; 
 R4, R5 and R6 each independently represent alkyl, aryl alkyl, hydroxy alkyl, amino alkyl, carboxy alkyl, sulfo alkyl or a polymerizable substituent, said substituent comprising said functional group and being of formula: 
 
       
       
         
           
           
               
               
           
         
         wherein m may vary between 0 and 50 and R is hydrogen or methyl. 
       
     
     
         7 . The acetal copolymer of  claim 1  being comprised in a lithographic printing plate coating solution. 
     
     
         8 . The acetal copolymer of  claim 7 , wherein said coating solution further comprises an iodonium salt having attached thereto at least one functional group capable of undergoing cationic or radical polymerization. 
     
     
         9 . The acetal copolymer of  claim 7 , wherein said coating solution further comprises a polymer binder having attached thereto at least one functional group capable of undergoing cationic or radical polymerization. 
     
     
         10 . The acetal copolymer of  claim 1  being comprised in a negative working lithographic printing plate. 
     
     
         11 . The acetal copolymer of  claim 2  wherein G1 is 
       
         
           
           
               
               
           
         
       
     
     
         12 . The acetal copolymer of  claim 4  where G2 is: 
       
         
           
           
               
               
           
         
         wherein:
 R is hydrogen or methyl; 
 R2 is C 1 -C 8  alkyl or alkoxy; 
 m and w may vary between 0 and 50; and 
 y is 1 or 2. 
 
       
     
     
         13 . The acetal copolymer of  claim 4  where G2 is: 
       
         
           
           
               
               
           
         
       
     
     
         14 . The acetal copolymer of  claim 1  wherein the acetal copolymer comprises more than one G3 segments that may be identical to or different from each other. 
     
     
         15 . The acetal copolymer of  claim 6  wherein Z1, Z2 or both Z1 and Z2 is phenyl or naphtyl.